Pneumatik-Bagger (3D)
About this app
Ein fahrbarer Bagger aus dem Nut-Zapfen-Baukasten, Teil für Teil nach Fotos des Originalmodells von etwa 1992 nachgebaut: Knickausleger mit zwei Zylindern, Parallelstreben, Stiel und Zweischalengreifer an drei Ventilen mit Rollenhebel. Luft strömt sichtbar durch die Schläuche, Kolben und Federn arbeiten im durchsichtigen Zylinder, und ein grauer Baustein soll auf die rote Platte.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
The basics
Pneumatics moves machines with compressed air. A single-acting cylinder extends while its 3/2-way valve lets air in; the force is pressure times piston area. When vented, the air escapes and the weight of the load, a spring or a rubber band push the piston back. Compressed air can only push, never pull. If one cylinder is not enough, two work side by side on one valve: twice the area, twice the force.
What you see
A 3D rebuild of an excavator made from groove-and-peg blocks, built around 1992 and transferred part by part from photos of the original. It rolls on four wheels. Two cylinders lift the boom on the mast, one cylinder swings the stick through parallel links, and a fourth closes the two shells of the grab via a rod. The cylinders are transparent and the pistons move visibly. A compressor fills the tank on the vehicle through a long hose and a throttle; air particles travel through the hoses.
Try it yourself
Switch on the compressor and wait for pressure. Open valve 3 and watch the rod push the axles of the shells down; close it and the rubber band opens the grab again. Then the task: grab the grey block, raise the boom, push the excavator over the red plate, lower and let go. The Values panel shows pressure, stroke and forces of each cylinder, the Original panel the photo of the real model.
Frequently asked questions
- How does a single-acting pneumatic cylinder work?
- Compressed air flows through one port into the cylinder and pushes the piston out. The return stroke is done by a spring inside the cylinder or an external force such as weight or a rubber band once the valve vents. It only works in one direction with air.
- What is a 3/2-way valve?
- A valve with three ports (supply, work line, exhaust) and two positions. In one position air flows to the cylinder, in the other it escapes to the atmosphere. It is used to control single-acting cylinders: fully out or fully in.
- How do you calculate the force of a pneumatic cylinder?
- The force is gauge pressure times piston area, F = p · A. A 14 mm piston has 154 mm²; at 0.3 bar (0.03 N/mm²) it pushes with about 4.6 N, two cylinders side by side with 9.2 N. Spring force and friction have to be subtracted.
- What can I do with the pneumatic excavator in the app?
- Switch the compressor and three valves, push the excavator and put a grey block on a red plate. You see air, pistons and springs at work, read pressure, stroke and forces, and find each part in the photo of the original model.
Subject: Engineering mechanics
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